Structures and vibration analysis of film bulk acoustic wave resonators

The wireless communication technology demands for smaller size, high frequency, high performance, low energy consumption, and low cost RF components. Current products based on dielectric or SAW resonators are not enough either due to the size or the circuit loss. Film bulk acoustic resonators (FBAR) are the latest technology offering small size and high frequency RF components to the fast growing personal wireless communication technology. We reviewed the current state-of-art of the FBAR technology and explained the working mechanism of FBAR. With two major vibration models, thickness-extension and thickness-shear, we also described the FBAR structure and principle of material selection. Furthermore, we analyzed the effect of electrodes on the vibration frequency, and explained the choice of quarter wavelength reflectors in the SMR. We want to provide essential concepts and knowledge about FBAR technology to engineers who are interested in studying it further. With enough knowledge on the vibration models and materials, the design method of FBAR and SMAR can be established with accurate analysis.